# New Method for the Determination of Lamotrigine in Human Saliva Using SPE-LC-DAD

## TL;DR

This paper introduces a new, comfortable method to measure lamotrigine levels in saliva, which could improve monitoring for bipolar disorder patients.

## Contribution

The first use of solid-phase extraction for isolating lamotrigine from saliva in analytical methods.

## Key findings

- The method showed linearity in the concentration range of 10–2000 ng/mL with R2 > 0.99.
- Intra- and inter-day precision had a coefficient of variation (CV%) of less than 15%.
- The method was successfully applied to measure lamotrigine in saliva from bipolar disorder patients.

## Abstract

(1) Background: The concentration of lamotrigine, an antiepileptic drug very often used in bipolar disorder, is most often determined in the blood, with many inconveniences. An alternative may be to use saliva as a diagnostic material for this purpose. The development of a method to determine lamotrigine in saliva as a biological material significantly improves patient comfort during sampling. The developed method uses solid-phase extraction for the isolation of the drug from saliva for the first time. (2) Methods: This study aimed to develop a method to determine lamotrigine in saliva using solid-phase extraction (SPE) for isolation and liquid chromatography with a diode array detector (LC-DAD) for quantitative analysis. (3) Results: The method was validated by determining its linearity in the concentration range 10–2000 ng/mL (R2 > 0.99), and the intra- and inter-day precision expressed as coefficient of variation (CV%) did not exceed 15%. (4) Conclusions: The developed method was used to determine the salivary concentration of lamotrigine in patients treated with the studied compound, confirming its usefulness in bipolar disorder (BD).